The invention relates to sampling and monitoring systems and methods. In particular, the invention relates to on-line sparging sampling and monitoring systems and methods.
Typically, a sampling system is used to monitor manufacturing processes, in which the sampling system may include analyzing capabilities. The sampling system should obtain a representative sample with minimal operations and time. While such sampling systems have been used in industry, these sampling systems may experience analytical problems, some of which may be attributed to sampling system features and mechanics.
Manufacturing processes may produce by-products, which need monitoring, such as by sampling and analyzing. A manufacturing process may produce volatile organic compound (VOCs) by-products at a process discharge, such as, but not limited to, an aqueous discharge. Typically, VOCs can comprise mixtures of polar and non-polar hydrocarbons. VOCs can pose analytical problems for conventional monitoring and sampling systems. Polar and non-polar hydrocarbons generally require two different and distinct processes for sampling from an aqueous discharge. Non-polar VOCs, such as, but not limited to, benzene, toluene, and aliphatic hydrocarbons including hexane, are generally sampled with a purge-and-trap method and analyzed by gas chromatography (gc). However, polar VOCs, including but not limited to acetone, methanol, and other alcohols, are typically sampled by sparging or dynamic headspace sampling and analyzed by gas chromatography. Alternatively, polar VOCs can be sampled by direct injection gas chromatography (gc).
If a monitoring system requires collection of samples (often known as xe2x80x9cgrab samplesxe2x80x9d), time delays between the actual sampling operation and the analyzing of the samples often occur. These time delays may be so long that the value of a sample is diminished because the by-product sample may not be reflective of actual and real-time by-products. Thus, the time delay is undesirable.
Further, the aqueous discharge being monitored may often contain sediment and particulates. Conduits in conventional sampling systems may be configured too narrowly and be constricted so that fouling and blockage by sediments or particulates often occurs and interrupts monitoring. Thus, filtering of influent aqueous discharge is needed. The filters in conventional monitoring systems need to be cleaned and replaced, which is both inefficient and un-economical.
Improvements and advancements have been proposed for sampling systems. For example, advancements have been made in on-line sampling systems including, but not limited to, sample validation techniques, modular designs, new sampling system materials, probe enhancements including fiber-optic probes, enhanced membrane technology, and re-designed valves and filters. These on-line sampling system advancements have been useful. However, if these on-line sampling system advancements are applied to old sampling system technology, analytical problems may still arise since the sampling system is limited by the old sampling system technology of the on-line sampling system.
Therefore, improvements in on-line sampling technology are needed to keep up with current process analyzer technology. Further, a sampling system that is able to sample and monitor polar and non-polar VOCs is needed. Furthermore, a sampling system that is able to sample and monitor without delays, which are associated with some conventional sampling systems, is needed
An aspect of the invention provides on-line sparging sampling system and method that sparges polar and non-polar volatile organic compounds from aqueous discharge. The system comprises a network of tubular members that are interconnected to each other to define a fluid passage, in which the network of tubular members comprises an inlet for influent aqueous discharge into the network of tubular members and an outlet for discharge of aqueous discharge from the on-line sparging sampling and monitoring system; a sparger disposed in the network of tubular members, in which the sparger is disposed between the inlet and the outlet of the aqueous discharge so that aqueous discharge flows by the sparger, the sparger providing inert non-reactive gas to the on-line sparging sampling and monitoring system; and at least one analytic device connected to the on-line sparging sampling and monitoring system for analyzing volatile organic compounds in the aqueous discharge. The aqueous discharge forms an aqueous discharge portion and a headspace during flow through the network of tubular members. The sparger provides the inert non-reactive gas to flow through the aqueous discharge portion. The inert non-reactive gas partitions volatile organic compounds from the aqueous discharge portion to the headspace. Thus, polar and non-polar volatile organic compounds can be analyzed by the at least one analytic device.
Another aspect of the invention sets forth a method for on-line sparge sampling by sparging polar and non-polar volatile organic compounds from aqueous discharge using an on-line sparging sampling and monitoring system. The method comprises providing a network of tubular members that are interconnected to each other to define a fluid passage; providing an inlet for influent aqueous discharge into the network of tubular members and an outlet for discharge from the on-line sparging sampling and monitoring system; disposing a sparger between the inlet and the outlet of the aqueous discharge; flowing aqueous discharge by the sparger; providing inert non-reactive gas from the sparger to flow through the aqueous discharge in the on-line sparging sampling and monitoring system; flowing the inert gas through the aqueous discharge; forming a aqueous discharge portion and a headspace in the network of tubular members during aqueous discharge flow through the network of tubular members; monitoring and analyzing the sparged aqueous discharge in the on-line sparging sampling and monitoring system for volatile organic compounds using at least one analytic device; and partitioning volatile organic compounds from the aqueous discharge portion to the headspace so that polar and non-polar volatile organic compounds can be analyzed.
These and other aspects, advantages and salient features of the invention will become apparent from the following detailed description, which, when taken in conjunction with the annexed drawings, where like parts are designated by like reference characters throughout the drawings, disclose embodiments of the invention.